Ministry of Earth Sciences
Weather systems & associated Precipitation during Week 1  and Week 2 
Cold wave conditions likely in some parts over western Himalayan region and in isolated pockets over northwest, central & eastern India
Below normal day temperatures by 1-3°C could prevail over plains of northwest India, central & adjoining peninsular India & above normal by 1-3°C over eastern India
Scattered to Fairly widespread rainfall/snowfall over Jammu, Kashmir, Ladakh, Gilgit, Baltistan & Muzaffarabad; isolated to scattered rainfall/snowfall over Himachal Pradesh, Uttarakhand and isolated rain/thundershowers over adjoining plains of Northwest India
Isolated to scattered rainfall over Tamil Nadu, Kerala & Lakshadweep Islands
Minimum temperatures likely to remain below normal by 1-3°C over major parts of the country outside northeastern states
According to the National Weather Forecasting Centre of the India Meteorological Department :
Rainfall for week 1: 
- An active Western Disturbance is likely to affect Western Himalayan Region from 26th which could cause Scattered to Fairly widespread rainfall/snowfall over Jammu, Kashmir, Ladakh, Gilgit, Baltistan & Muzaffarabad; isolated to scattered rainfall/snowfall over Himachal Pradesh, Uttarakhand and isolated rain/thundershowers over adjoining plains of Northwest India during 27th-28th December, 2020.
- Easterly waves are likely to cause isolated to scattered rainfall over Tamil Nadu, Kerala & Lakshadweep Islands during week 2.
- Cumulatively, near normal rainfall activity over major parts of the plains of the country outside Tamil Nadu & south Kerala where it could be below normal during week 1. Below normal rain/snow also likely over Western Himalayan Region during week 1. .
Rainfall for Week 2 
- An easterly – westerly interaction leading to a wet spell over central India & northern plains is also likely during later part of week 2.
- Rainfall is likely to be above normal rainfall over Tamil Nadu, Kerala & Lakshadweep Islands during week 2. Below normal rain/snow also likely over Western Himalayan Region and adjoining northwestern plains of India during week 2. .
Temperature/fog for week 1 & 2: 
- Minimum temperatures likely to remain below normal by 1-3°C over major parts of the country outside northeastern states during week 1. Northeastern states likely to get above normal temperature during week 1. .
- Cold wave conditions likely in some parts over western Himalayan region and in isolated pockets over northwest, central & eastern India during 2nd half of the week 1. Cold wave conditions also likely at isolated pockets of Interior Odisha & adjoining Chhattisgarh during the same period.
- Minimum temperatures likely to above normal by 2-4°C over central India and northeastern states during week 2. However, it is likely to remain below normal by 2-3°C over plain of northwest India and Bihar, and 1-2°C above normal over Odisha & adjoining Chhattisgarh during the week 2. .
- Cold wave conditions likely in some parts over western Himalayan region and in isolated pockets over northwest India during 1st half of the week 2. In general, it could remain less prevalent in week 2 outside Northwest India.
- During week 2, there would be rise in minimum temperatures over northwest, Central and eastern India as compare to week 1. .
Maximum Temperature:
- Below normal day temperatures by 1-3°C could prevail over plains of northwest India, central & adjoining peninsular India & above normal by 1-3°C over eastern India  during week 1. Similar pattern could continue in week 2, but with slight warming of days, as compared to week 1 .
Dense to very dense fog forecast for week 1
Dense to very dense fog in some pockets very likely over Punjab in the morning hours of 25th and isolated Dense fog in the morning hours of 26th. Dense fog in isolated pockets over northern parts of Uttar Pradesh and Haryana in the morning hours of 25th & 26th December, 2020. Fresh spell of dense fog likely over plains of north India from 29 Dec.
Cyclogenesis: There is no probability of cyclogenesis over north Indian Ocean during week 1 and week 2.
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